Vietnam is a rather safe destination for solo female travelers and backpackers as there are very few violent crimes, but there are some things to watch out for. There are some scams like the ‘free’ shoe cleaning scam that commonly occur in the bigger cities like Hanoi, Ho Chi Minh, and Nha Trang. Additionally, there are some cases of drive-by snatching so store your valuables while strolling through the cities.
The streets of the cities are incredibly busy, so driving there is not for the faint of heart or those without prior scooter experience. Be quick when crossing streets and keep looking left and right as you walk. Check the price in advance to ensure that you are not overcharged when taking a taxi. I recommend using grab as the app shows you the price in advance and the rides are usually less expensive than a taxi.
Mind warnings about undetonated explosives. Many more remote areas have yet to be cleared of landmines, so do everyone a favor and stay on the path when exploring rural areas.
Avoid drinking tap water. Additionally, it is advised to use insect repellent and sunscreen. At times there is a lot of air pollution, so check the air quality if you are sensitive to it. Some areas, like the Mekong Delta, have a higher Dengue fever and malaria risk.
Vietnam is a communist country, so do not take photos of the military and avoid political debates. Stay away from drugs as punishment for drug offenses is severe.